Chapter 1: The Microbial World

Question 1

A scientist discovers a small particle that can replicate and examines it in the lab. What finding would indicate that the particle is not a living cell?

Answer 1

It has an RNA genome with no DNA

Question 2

LUCA is ______________

Answer 2

the last common ancestor of Bacteria and Archaea

Question 3

What is a reason that the term prokaryote may be confusing?

Answer 3

Archaea and Bacteria both have prokaryotic cells but are very different domains.

Question 4

What is the difference between transcription and translation?

Answer 4

Transcription produces various types of RNA, and translation produces proteins.

Question 5

What best describes why microbes have been so important in answering general questions about how genetic material is copied?

Answer 5

Many microbes are easy to grow in a test tube or in a dish in the lab, making them easy to study.

Question 6

If you performed a Gram stain on a gram-negative cell but forgot to add safranin, the cell would appear _____________

Answer 6

unstained

Question 7

Eukaryotic cells can be distinguished from prokaryotic cells by _________________

Answer 7

having linear chromosomes

Question 8

What are types of macromolecules?

Answer 8

Ribosomal protein, DNA

Question 9

Compared with a large cell, a small cell has a surface area-to-volume ration that is _________

Answer 9

larger.

Question 10

If you wanted to determine whether intercellular communication was occurring between bacteria, what would be the best thing to study?

Answer 10

How some bacteria produce toxins only when their population density is high

Question 11

A cell with an unusually thick cell wall is most likely ____________

Answer 11

able to resist pressure well.

Question 12

What observation would be consistent with classifying a newly discovered microbe within Domain Archaea?

Answer 12

It produces methane.

Question 13

Why is it important that rRNA used to construct phylogenies is highly conserved?

Answer 13

Genetic material with a high mutation rate would change too quickly to allow the detection of gradual evolutionary change.

Question 14

A researcher obtains a sample of water from a lake. He immediately analyzes the sample to detect all bacterial DNA and then adds the sample to culture to see what species will grow. What do you predict that he will find?

Answer 14

There will be many more species of bacteria identified through DNA than in the cultures

Question 15

You are able to view a specimen at very high magnification using a bright-field microscope, but the resolution is very low. What will the specimen look like?

Answer 15

The specimen will be large but blurry, and it will be difficult to distinguish features.

Question 16

The name for the technique used to prevent contamination of cultures is called ______________

Answer 16

aseptic technique

Question 17

If you are given a micrograph, what characteristic would let you know that it was taken using scanning electron microscopy compared with another type of microscopy?

Answer 17

It shows 3D outer structures

Question 18

The researcher who developed rigorous criteria for identifying the causative agent of a disease was ____________

Answer 18

Robert Koch, Koch’s postulates.

Question 19

What is one reason that a particular bacterium may develop antibiotic resistance very quickly?

Answer 19

It receives an antibiotic resistance gene through horizontal gene transfer.

Question 20

Stains are used because _________________

Answer 20

they increase contrast and can be used to distinguish between types of structures or cells.

-bright background
-differential stains- gram -/+

Question 21

Over many generations, a small group of bacteria has been separated from others of its species. This small group appears to be thriving even though it has much less access to water than others of its species. What do you predict to be true of these bacteria compared with others of the same species?

Answer 21

The cells will have adaptations to conserve water

Question 22

Microbial medium can be ______________

Answer 22

solid or liquid

Question 23

While analyzing fungal DNA, a researcher detects a gene that is almost identical to a common bacterial gene but not similar to any genes previously detected in well-studied fungi. What is the most likely explanation?

Answer 23

The gene was transferred horizontally from the bacterium to the fungus.

Question 24

What is one reason that a researcher might prefer to use a dark-field microscope rather than a bright-field microscope to view a cell?

Answer 24

Cell motility can be observed more easily without a stain

Dark-field= easier to view LIVING cells without stains that may kill the cells

Question 25

What best describes any microorganism that can cause disease?

Answer 25

pathogen

Question 26

Louis Pasteur

Answer 26

disproved spontaneous generation- sterilization technique- swan neck.
-rabies vaccine
-pasteurization

Question 27

Sergei Winogradsky

Answer 27

defined chemolithotrophy- obtain energy and carbon from inorganic sources

Question 28

Carl Woese

Answer 28

used rRNA to examine evolutionary relationships and developed a tree of life.